Longer telomeres after treatment with lithium

A new study from Karolinska Institutet reveals that lithium treatments for bipolar disorder can sometimes increase the length of so-called telomeres, the sections of DNA at the end of the chromosomes in the cell nucleus. The shortening of these telomeres has been linked to ageing, stress and mental disease, and the researchers now hope that their results will mark the first step on the path to a more individualised treatment of bipolar disorder.

"Lithium has been one of the cornerstones of bipolar therapy for decades," says Dr Lena Backlund, psychiatrist and researcher at Karolinska Institutet's Department of Molecular Medicine and Surgery. "Yet we also know that patients respond differently to the treatment. Our study, which provides new knowledge on how a drug affects the telomeres, opens up avenues for a more individualised form of treatment."

Bipolar disorder is a congenital and severe mental illness involving recurrent periods of mania and depression that affects 2-3 per cent of the population. The disorder is chronic and the cause of great suffering for the patient as well as their families, friends and colleagues. Although a well-managed, prophylactic lithium treatment has proved to be the most important determinant of a positive prognosis, only around fifty per cent of patients respond well to it.

The present study, which is published in the scientific journal Translational Psychiatry, involved 256 patients diagnosed as bipolar and receiving lithium, and 139 healthy controls. The results show that the patient group on average had much longer telomeres than the control group, and that the patients who responded well to the lithium treatment had longer telomeres than those who did not.

Previous studies have demonstrated that telomeres shorten with age, stress and mental illness, and that exercise and some drugs seem to restore their length. However, to date there have been no studies on telomere length linked to bipolar disorder and its treatment with lithium.

"Bipolar disease that is not adequately treated often causes considerable suffering and carries a high risk of suicide," says study co-author Lina Martinsson, doctoral student at the Department of Clinical Neuroscience. "It would therefore be of clinical value if we could predetermine the affects of lithium from a blood sample. We hope that our work will have a knock-on effect."

The study was financed by grants from the Swedish Research Council, the Centre for Psychiatric Research (Karolinska Institutet), Psykiatri Sydväst (part of the Stockholm County Council), the Söderström-Königska Foundation and the Fredrik and Ingrid Thuring Foundation.